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Old 07-23-2014   #1
witttom
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Question Bleeding

I'm finally getting around to a little project that I should have addressed years ago. The rear brakes of my Baghira have never been right. Weak when I first got it, I bled them and they were strong for months. Became soft again, bled them, fine. This cycle went on for a long while, with the intervals getting shorter and shorter. I never could find a leak, it never needed additional fluid, but it was obviously sucking air into the system somewhere, albeit a very tiny bit. Easy to bleed, and never really a problem. So I did not do anything more than that.

Then the intervals started getting smaller, and last September in the middle of the Smoky Mtns on some roads that weren't really roads, the rear master decided that it didn't want to hold any pressure for more than a couple minutes at a time. I could bleed them, and five minutes later they were gone again. That was pretty much the last time I had rear brakes. It was always my intent to address it once I got home, but 94.7% of my riding is done on pavement (well, maybe not on pavement, but not really off road). I've not really NEEDED rear brakes.

A couple months ago, I decided that I would swap in a Suzuki MC, but then figured out that it was really bigger than what I needed and would take a little bit of fab work to do it. I bled the original Grimeca MC at that time, got my brakes back for a while, and forgot about it again.

I was recently digging through a pile of parts in my workshop looking for something different, and came across a Brembo MC from a Yamaha R6 (thanks jdanhires!). It was virtually the same size, bolted up the same, reservoir fitting in the same location... and thought, "Hmmm! looks like a match!". I spent a long while swapping it out, hooking up the linkage, and then trying to bleed it. I could never get any pressure out of it. It did not seem to be particularly happy with the throw-action from the pushrod anyway (I think the Grimeca may have a longer stroke), and I abandoned that idea, eventually swapping the Grimeca back in.



I can live without rear brakes, BUT I plan to use this bike as a loaner in September, with potentially several different riders over a period of a few days. I do not want to loan it out to THEM without rear brakes.

So now before I move onto the next step, whatever that step may be... either adapting a larger MC from a different bike, or isolating the problem to a different area, I really want to confirm that my Grimeca MC is truly the culprit. Now back in place and filled with brake fluid, I'm TRYING to build pressure back up but have been unsuccessful in doing so. I believe I have a big bubble in the highest point of the system, and I just can't push it through, nor is it pulling any fluid in from the reservoir. I had a similar situation a long while back when swapping out a Triumph MC, and if I recall correctly, eventually had to use a vacuum bleeder to get it going.

I don't have a vacuum bleeder, and in my recent online shopping, I see that there are an infinite number of variations ranging from a few bucks to a few hundred bucks. I don't know what to get, I'm really not sure what I'm even looking at, I don't want to invest a ton of money into this, but I also don't want to buy the cheapest crap that isn't gonna work for me. I'm planning on stopping in at a local automotive parts store soon, and see what they have. But... I still don't know what I want. What do I want?
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Old 07-23-2014   #2
AnswerMeister
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Re: Bleeding

I have a hand pump bleeder that you can use. I can leave it on the front porch tomorrow if you need it. If the bubble is in the high point, have you tried lifting the bike so that is no longer the high point? A strap to the rear frame with a ratchet strap or come-a-long over a tree branch you should be able to make the rear wheel the high point.

Or put the bike nose down on a set of steps, that will get the back end up high.
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Old 07-23-2014   #3
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Re: Bleeding

Tom: I've got a vacuum bleeder as well. I'm watching my dad today for awhile midday, but could pop over later in the PM and see if we can get it fixed. Based on reading your post, I'd hazard a guess that you may have issues with the Grimeca MC, either seals or possibly a blocked port, most likely the return side. Should be back around 3-ish. Lemeno.
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Old 07-23-2014   #4
ducmays
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Re: Bleeding

Sounds like 1 thing going on here. The problem isnt the master cylinder nor the motorcycle. Its gonna make it harder to cure this issue swapping parts in from other bikes. You have a air bubble. Use a mighty vac or remove master cylinder and rotate it a bit. They need to be bled. It will cure your issue. Your not losing any fluid so its not a line issue. Also check the pushrod adjustment after you put the stock master back on. Hope the R6 part dint mess anything up if you mashed on the rear brake hard enough. If the pushrod is to short, it sucks the piston in to far. If its too long it doesn't release the brakes properly.
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Old 07-23-2014   #5
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Re: Bleeding

Quote:
Originally Posted by ducmays View Post
Sounds like 1 thing going on here. The problem isnt the master cylinder nor the motorcycle. Its gonna make it harder to cure this issue swapping parts in from other bikes. You have a air bubble. Use a mighty vac or remove master cylinder and rotate it a bit. They need to be bled. It will cure your issue. Your not losing any fluid so its not a line issue. Also check the pushrod adjustment after you put the stock master back on. Hope the R6 part dint mess anything up if you mashed on the rear brake hard enough. If the pushrod is to short, it sucks the piston in to far. If its too long it doesn't release the brakes properly.
How is it that you've been a member here for 3-1/2 years, and yet this is only your second post??


Quote:
Originally Posted by icantdrive55 View Post
Tom: I've got a vacuum bleeder as well. I'm watching my dad today for awhile midday, but could pop over later in the PM and see if we can get it fixed. Based on reading your post, I'd hazard a guess that you may have issues with the Grimeca MC, either seals or possibly a blocked port, most likely the return side. Should be back around 3-ish. Lemeno.
I may take you up on that offer. Having an extra set of eyeballs on this may help with my sanity. I have beer.

Quote:
Originally Posted by AnswerMeister View Post
I have a hand pump bleeder that you can use. I can leave it on the front porch tomorrow if you need it. If the bubble is in the high point, have you tried lifting the bike so that is no longer the high point? A strap to the rear frame with a ratchet strap or come-a-long over a tree branch you should be able to make the rear wheel the high point.

Or put the bike nose down on a set of steps, that will get the back end up high.
Appreciate the offer, but let's see if Bubba can straighten me out.
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Old 07-23-2014   #6
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Re: Bleeding

looks like I logged onto my old account. Didnt know I had a old account. It was already logged in on my work computer. Strange. Did you get it sorted out?
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Old 07-23-2014   #7
Dave Bannister
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Re: Bleeding

When I can't get fluid down to the bleeder screw I first loosen the brake connection on master cylinder and get fluid inside master.. you must prime the pump so to speak... then work your way down... I would also recommend that you pick up a rebuild kit and rebuild that master cylinder... Your plunger could be internally passing through and that is why you are not pumping fliud and you think you have air in the lines because you are unable to build pressure by moving fluid to your calipers and pushing your pads which gives you pressure ( brake pedal feel)
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Old 07-23-2014   #8
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Re: Bleeding

I have a Mity-Vac, I use it on an empty system to get the fluid into the lines. It doesn't always work to get the air bubbles out. Great for exchanging system fluid though.

You might have to crack the fitting at the master cylinder to get fluid out of the piston before you charge the lines....

I have had similar problems with my Magna, I bought speed bleeders to replace the stock units. That really cut down on my entrained air problems, makes the occasional bleeding much faster.

I have seen a brake line bleeder bolt that might fit your master cylinder...

http://www.v4market.com/Brakes-Banjo...der_p_125.html

The person running the V4 Market is having some family issues at the moment, you might be able to find something like this else where though.

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Old 07-23-2014   #9
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Re: Bleeding

You might try hanging a good(heavy) weight on the brake pedal and let it sit for a couple days.
This trick has worked for me in the past especially with Euro bikes?
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Old 07-23-2014   #10
jdanhires
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Re: Bleeding

Have you tried removing the MC and roatating it as you bleed it? It's easier than moving the entire bike.
Failing that, I've used a Phoenix brake bleeder in the past - it does a great job of force fluid from the MC to the brakes - reverse of what normal bleeding does.

John
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Old 07-23-2014   #11
witttom
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Re: Bleeding

Bubba came over earlier this evening with a vacuum bleeder. He saw what I saw, which is really what I wanted him to see. We opened up the original Grimeca master, cleaned it out real good, inspected it, put it back in, compressed the caliper and confirmed that we were getting fluid back up through the line, flushed the line, and sucked all the air out of it. It would appear that the master is not generating enough pressure, despite appearing to be in good shape internally. That's where we stopped. Took only a couple seconds to describe that process, but can assure you we spent quite a bit more time than that actually going through those steps. I have some other things that I plan to do to confirm that the master is the culprit (or alternatively point me in a different direction), but I've not had the opportunity to get back to it this evening. Maybe tomorrow.

Additionally, while were were pulling apart the Grimeca, we also disected the R6 master, or what I THOUGHT was an R6 master. As it turns out (which I discovered after Bubba left) that this is a case of mistaken identity. It's not an R6 master after all, but an Aprilia [Brembo] master. Gee, I wonder where that came from. The Brembo looked pretty nasty inside, and we're betting that it was not good. It DOES however closely match the Grimeca as far as size, shape, mounting locations, etc... and potentially leaves me with some alternative options, depending on what route I end up taking.
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Last edited by witttom; 07-23-2014 at 10:50 PM.
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Old 07-24-2014   #12
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Re: Bleeding

I realize I'm late to the game - but as a recent buyer and user of this:

http://www.harborfreight.com/brake-f...der-92924.html

I can highly recommend it. I used this tool to suction out and replace all the brake fluid in 3 cars, 2 motorcycles, then moved on to the neighbor's house and did his Durango and Mustang while he fed me beers. All in one day.

Very easy to use. Very happy w/ the results. I began using it after replacing rear wheel cylinders on my truck, it was so quick and easy that I rolled under my other two cars and did them, then the bikes.
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Old 07-24-2014   #13
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Re: Bleeding

Quote:
Originally Posted by witttom;164136

Additionally, while were were pulling apart the Grimeca, we also disected the R6 master, or what I THOUGHT was an R6 master. As it turns out (which I discovered after Bubba left) that this is a case of mistaken identity. It's not an R6 master after all, but an Aprilia [Brembo
master.
Er, yeah, that master is from an '01 RSV if you need to order a rebuild kit.

John
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Old 07-24-2014   #14
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Re: Bleeding

Quote:
Originally Posted by witttom View Post
Additionally, while were were pulling apart the Grimeca, we also disected the R6 master, or what I THOUGHT was an R6 master. As it turns out (which I discovered after Bubba left) that this is a case of mistaken identity. It's not an R6 master after all, but an Aprilia [Brembo] master. Gee, I wonder where that came from. The Brembo looked pretty nasty inside, and we're betting that it was not good. It DOES however closely match the Grimeca as far as size, shape, mounting locations, etc... and potentially leaves me with some alternative options, depending on what route I end up taking.





hmmmm...I've got one of those toooo... me thinks the engine heat and location[Ape] lead to it's/their downfall, probably why you found it, lol...the only way I can get ANY rear brake on my T is with a mighty-vac!!
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Old 07-25-2014   #15
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Re: Bleeding

I had a brake problem with my old Goldwing. I couldn't figure out why it wouldn't pump up. I tried every bleeding trick I could think of. Turns out the brake lines were so old that they were stretching or ballooning out when I hit the brakes. It made feel that there was air in the lines. My first clue was in the winter they would work decent. As summer rolled in they would progressively get worse as the rubber got warmer. I put some Spiegler lines on it and its perfect now. If you are running a rubber line it may something to consider.
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